This invention relates generally to apparatus for controlling rotational speed of an internal combustion engine used for vehicles, such as automobiles, and particularly to such apparatus used with rotational force transmitting system including a clutch and a transmission.
In the operation of an internal combustion engine used for a motor vehicle, if the rotational speed of a clutch at its engine side is not equal to the rotational speed of the clutch at its transmission side during gear change performed when the motor vehicle is driven, undesireable phenonmena, such as acceleration or deceleration shock, torsion of the propeller shaft, wear of the clutch, are apt to occur at the time of engagement of the clutch. These undesirable phenonmena would deteriorate smooth and stable travelling of the motor vehicle and cause mechanical damages or deterioration of the clutch, propeller shaft and other parts.
This problem may be resolved if the rotational speed of the clutch disc at its engine side is controlled to be equal to the rotational speed of the other clutch disc at its transmission side, namely the engine speed equals the rotational speed of an input shaft of the transmission. According to a conventional apparatus, such as disclosed in a Japanese patent provisional publication No. 57-140531, the engine speed is controlled to be equal to a target speed which is obtained in accordance with engine load. However, with such conventional apparatus, the above-mentioned problems are not effectively resolved, and therefore, vehicle drivers have hitherto been required to be skillful enough in connection with the operation of the accelerator pedal and the clutch pedal to avoide possible damages of the clutch and its peripheral parts and to provide smooth transmission of rotational force from the engine to the propeller shaft.